Group 11: Samuel Axelrod, Joshua Bary, Zachary Currier, Ermira Murati

Dartmouth Formula Racing

1

1
Background Information

Background

FSAE Student Design

Formula Hybrid

Formula Hybrid Competition
Presentation 100
Desig...
Introduction

FALL TERM FOCUS

WINTER TERM FOCUS

• Understanding the Car

• Installation, Implementation, Assembly

• Des...
Problem Statement

The 2011 Dartmouth Formula Hybrid
racecar does not possess a reliable or
robust mechanical system that ...
Need Statement

DFR needs to win the 2012 Formula Hybrid
Competition.
Our group needs to design a functional
drivetrain an...
Deliverables

Primary Deliverables:

1. Implement a mechanism to start the racecar every time
2. Design a system that can ...
Design Overview - Design Objectives

Simplicity — Time is our scarcest resource
Reliability — Failure rate must be very ne...
Design Overview - Constraints

Cost
The DFR budget is not unlimited, and our combined activities and purchases
(including ...
Design Overview - Failure Strategy

• True dynamic loads are hard to predict

• All power is transmitted through the chain...
Engine/Starter - Overview

Previous design and reasons:
‒
‒
‒
‒

Fuel-injected internal combustion engine
Easy engine mapp...
Engine/Starter - Specifications

Specification

Justification

Quantification

Baseline

Target

Cost

DFR has a limited b...
Engine/Starter - Decision Matrix

Starter
Specification Weight

High
Voltage

Starter
Motor

Internal
Starter

Mechanical
...
Engine - Methodology, Work Accomplished

•

Design mounts and mount the engine

•

Alter wiring harness to match the 2005 ...
Engine - Finite Element Analysis

Factors of Safety: Front 4.5; Middle 1.1; Rear 1.9

Dartmouth Formula Racing

14

14
Engine/Starter - Testing

• Testing engine on the bench mounted in the car
• Drove the car on several track days
–

Raceca...
Engine/Starter - Specifications

Specification

Quantification

Baseline

Target

Actual

Cost

Price ($)

<$1000

<$500

...
Shifter Overview

• 2011 team designed a pneumatic paddle-shifting system

• Clutch-less upshifts and downshifts using spa...
Shifter - Specifications

Specification

Justification

Quantification

Baseline

Target

Cost

DFR has a limited budget a...
Shifter - Specifications (Continued)

Specification

Justification

Quantification

Baseline

Target

Size

The car has li...
Shifter - Decision Matrix

Shifter
Specification

Weight

Cost

3.57%

Electric
Solenoid
-1

Pneumatic (existing
system)
0...
Shifter - Design Overview

• Last year – open-loop pneumatic system
Compressor

Pressure
Switch

Air tank

Regulator

Padd...
Shifter - Design Overview

• This year – closed-loop pneumatic system
Compressor

Pressure
Switch

Air tank

Regulator

Pa...
Shifter - Methodology, Work Accomplished

• Cylinder Sizing
– Measured force and distance required to shift
– Purchased Bi...
Shifter - Methodology, Work Accomplished

• Shifter control
– Moved from Arduino to Vehicle Control Unit (VCU)
– VCU alrea...
Shifter - Testing

• Bench test
– Ran through the gears in sets of 20
– Listened for shift and monitored
wheel speed

• Tr...
Shifter - Specifications

Specification

Quantification

Baseline

Target

Actual

Cost

Price ($)

< $1000

<$500

$350

...
Drivetrain - Overview

• Last year’s configuration was
designed to allow the electric motor
to start the internal combusti...
Drivetrain - Specifications

Specification

Justification

Quantification

Baseline

Target

Cost

DFR has a limited budge...
Drivetrain - Decision Matrix

Drivetrain
Specification

Weight

Current System

Switch Belt to
Chain

Clutch-less
System

...
Drivetrain - Alternatives

1. Hybrid Type – Series or Parallel
2. Belt or Chain
3. Drivetrain Component Geometry
One Chain...
Chain Tensioning

Adjustable motor and differential

Dartmouth Formula Racing

31

31
Drivetrain - Motor Shaft

Alternatives

• Shaft with welded sprockets
- Simple
- Machinable

• Splined Shaft
- Elegant des...
Drivetrain - Chain Guards

• 0.125‖ x 2½‖ Stock
• Combine to cover both chains entirely
• Mount to frame and rear engine m...
Drivetrain - FEA Analysis

Electric Motor Shaft

Dartmouth Formula Racing

34

34
Weld Analysis

• Analyzed the welds between the motor shaft and the sprockets
• Static Analysis
– Factor of Safety = 1

• ...
Drivetrain - FEA Analysis

Bearing Mount

Dartmouth Formula Racing

36

36
Drivetrain - FEA Analysis

Motor Mount

Dartmouth Formula Racing

37

37
Drivetrain - Differential

• Taylor Race Engineering - 4:1 Automatic
Torque Biasing (ATB) Differential
• One wheel can hav...
Drivetrain - Specifications Evaluation

Specification

Quantification

Baseline

Target

Actual

Cost

Price ($)

<$1000

...
Drivetrain - Overall Evaluation

Did we improve over previous designs?
–
–
–
–
–

Easy, lasting chain tensioning
No alignm...
Economic Analysis – Market Analysis

•

Target Market : Amateur weekend racecar
drivers

•

SCCA has over 55,000 members t...
Future Design Work

• Final Drive Ratio
– Will choose a final drive ratio after more driving, with a better understanding
...
Deliverables

1. Installed the CRF250X with an electric starter so that our
racecar starts every time
2. Improved the pneu...
Moving Picture
Thank you!
Professors Douglas Van Citters and John Collier
Douglas Fraser
Jason Downs
Christian Ortiz
Graham Keggi
Review ...
Questions?

Dartmouth Formula Racing

46

46
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  • The 2011 team created an intricate drive system which was extremely difficult to align. In this system, the elect
  • This is a potential weak point of our system despite the low odds the welds will fail and the success we have had driving with it so far
  • We have been able to drive the car since February and so far the drivetrain components have performed as designed. All of our specifications have been met and this solution fulfills the deliverable of a system that efficiently delivers power from…
  • Final presentation v final

    1. 1. Group 11: Samuel Axelrod, Joshua Bary, Zachary Currier, Ermira Murati Dartmouth Formula Racing 1 1
    2. 2. Background Information Background FSAE Student Design Formula Hybrid Formula Hybrid Competition Presentation 100 Design 200 Acceleration 150 Autocross 150 Endurance 400 2007 2008 99 100 200 127 DNF 150 DNF 95 108 110 Dartmouth Formula Racing 2009 91 192 124 DNF DNF 2010 85 182 118 77 105 2011 74 185 DNF DNF 123 2012 W 2 2
    3. 3. Introduction FALL TERM FOCUS WINTER TERM FOCUS • Understanding the Car • Installation, Implementation, Assembly • Designing Systems • Rules Compliance • Fabricating components • Driving, Testing, Troubleshooting Dartmouth Formula Racing 3 3
    4. 4. Problem Statement The 2011 Dartmouth Formula Hybrid racecar does not possess a reliable or robust mechanical system that interfaces well with the driver Dartmouth Formula Racing 4 4
    5. 5. Need Statement DFR needs to win the 2012 Formula Hybrid Competition. Our group needs to design a functional drivetrain and integrate all mechanical systems by January to allow for optimization, so that the team can complete all events at competition. Dartmouth Formula Racing 5 5
    6. 6. Deliverables Primary Deliverables: 1. Implement a mechanism to start the racecar every time 2. Design a system that can shift consistently 3. Redesign the drivetrain to eliminate complexity and allow for improved alignment 4. Work with the Electrical Powerplant and Data Management groups to install and test their systems on the racecar Dartmouth Formula Racing 6 6
    7. 7. Design Overview - Design Objectives Simplicity — Time is our scarcest resource Reliability — Failure rate must be very near zero Durability — We plan for extensive testing and driving Modularity — They will thank us next year Transparency — Feedback critical for testing Dartmouth Formula Racing 7 7
    8. 8. Design Overview - Constraints Cost The DFR budget is not unlimited, and our combined activities and purchases (including other 89/90 groups and DFR team projects) cannot exceed the collected funds of $8,000. Size The overall size of the frame has been finalized, so every component must be designed to a specific size that will fit well in the assembly. Rules Compliance We cannot race if we break any of the Formula Hybrid rules. Safety As aspiring engineers, rules of ethical conduct require us to put the safety of all individuals above any other considerations. Dartmouth Formula Racing 8 8
    9. 9. Design Overview - Failure Strategy • True dynamic loads are hard to predict • All power is transmitted through the chain • First part to fail should be the easiest to replace • Design components so the chain is first to fail Dartmouth Formula Racing 9 9
    10. 10. Engine/Starter - Overview Previous design and reasons: ‒ ‒ ‒ ‒ Fuel-injected internal combustion engine Easy engine mapping and tune-ability No cutting out through corners Problem: depended on high-voltage to start Needed to design a mechanism to start the engine: ‒ ‒ ‒ ‒ Honda CRF250X with built-in electric starter Start with high voltage system External starter motor on the CRF 250R Mechanical linkage Dartmouth Formula Racing http://twostrokemotocross.com/wpcontent/uploads/2009/12/Keihin_PWK.jpg 10 10
    11. 11. Engine/Starter - Specifications Specification Justification Quantification Baseline Target Cost DFR has a limited budget and numerous systems that must be improved Price ($) <$1000 <$500 Weight A lighter car will perform better, all else equal Pounds 10% increase from 2011 0% increase from 2011 Reliability The car must start every time, immediately. We cannot race if our car does not start. Number of times engine starts out of 20 Starts 75% of the time Starts 95% of the time Durability Our starter mechanism must be durable enough to handle testing and competition. We do not want to worry whether our starter could fail Number of broken parts No failures during during spring testing testing No failures during testing Size The starter must be small enough to leave room for the other systems on the car Volume 0% increase from 2011 Dartmouth Formula Racing 10% increase from 2011 11 11
    12. 12. Engine/Starter - Decision Matrix Starter Specification Weight High Voltage Starter Motor Internal Starter Mechanical Linkage Cost 0.00% 1 0 1 0 Weight 15.00% 1 0 1 0 Reliability 37.50% -1 1 1 0 Durability 25.00% -1 1 1 1 Size 22.50% 1 -1 1 0 -0.25 0.4 1 0.25 Dartmouth Formula Racing 12 12
    13. 13. Engine - Methodology, Work Accomplished • Design mounts and mount the engine • Alter wiring harness to match the 2005 CRF250X • Make and run new cooling hoses • Design and fabricate new angled air filter Dartmouth Formula Racing 13 13
    14. 14. Engine - Finite Element Analysis Factors of Safety: Front 4.5; Middle 1.1; Rear 1.9 Dartmouth Formula Racing 14 14
    15. 15. Engine/Starter - Testing • Testing engine on the bench mounted in the car • Drove the car on several track days – Racecar started quickly both hot and cold Dartmouth Formula Racing 15 15
    16. 16. Engine/Starter - Specifications Specification Quantification Baseline Target Actual Cost Price ($) <$1000 <$500 ~$300 Weight Pounds 10% increase from 2011 0% increase from 2011 <5% increase Reliability Number of times engine starts out of 20 Starts 75% of the time Starts 95% of the time Starts >95% of the time Durability Number of broken parts during spring testing No failures during testing No failures during testing No failures during testing Size Volume 10% increase from 2011 0% increase from 2011 0% increase Dartmouth Formula Racing 16 16
    17. 17. Shifter Overview • 2011 team designed a pneumatic paddle-shifting system • Clutch-less upshifts and downshifts using spark cut • Tested only on the dynamometer • Mounted on the car with universal joints, in a different location than designed • Shifted inconsistently • Could not find neutral Dartmouth Formula Racing 17 17
    18. 18. Shifter - Specifications Specification Justification Quantification Baseline Target Cost DFR has a limited budget and numerous systems that must be improved Price ($) < $1000 <$500 Weight A lighter car will perform better, all else equal Pounds 5lbs more than No weight last year increase over last year Reliability The driver will be required to shift Consistency of numerous times per lap and must shifting and be able to depend on the shifter finding neutral working when actuated. The shifter must be able to shift up, down and find neutral without missing shifts Shifts 98%, finds neutral 50% Shifts 99%, finds neutral 75% Durability The shifter should last through testing and competition without failing No failures during testing No failures during testing Number of broken parts during spring testing Dartmouth Formula Racing 18 18
    19. 19. Shifter - Specifications (Continued) Specification Justification Quantification Baseline Target Size The car has limited space. A new shifting system should not take up more space that the current pneumatic system Volume Same size as last year 10% smaller than last year Power Requirement The shifter may require power to function. If so, it must be a low enough requirement so that the power does not run out during the endurance race Power draw (W) 36W (last year’s system) No increase in power draw Speed The system must quickly execute shifts to improve acceleration and decrease lap times Time per shift 0.2 seconds 0.1 seconds Dartmouth Formula Racing 19 19
    20. 20. Shifter - Decision Matrix Shifter Specification Weight Cost 3.57% Electric Solenoid -1 Pneumatic (existing system) 0 Mechanical 0 Weight 4.76% 1 0 0 Reliability 26.19% 0 0 0 Durability 17.86% 0 1 1 Size 10.71% 1 0 -1 Power Requirement 16.67% Speed 20.24% -1 1 -1 1 1 -1 0.1547 0.2143 0.0358 Dartmouth Formula Racing 20 20
    21. 21. Shifter - Design Overview • Last year – open-loop pneumatic system Compressor Pressure Switch Air tank Regulator Paddles VCU Solenoids Cylinder Schematic of last year’s shifting system • Adjustments: – How long air flows into cylinder – Pressure in tank – Pressure at regulator Dartmouth Formula Racing 21 21
    22. 22. Shifter - Design Overview • This year – closed-loop pneumatic system Compressor Pressure Switch Air tank Regulator Paddles VCU Solenoids Cylinder Schematic of new shifting system • Adjustments: – How far cylinder travels – Pressure in tank – Pressure at regulator Dartmouth Formula Racing 22 22
    23. 23. Shifter - Methodology, Work Accomplished • Cylinder Sizing – Measured force and distance required to shift – Purchased Bimba Position-Feedback cylinder • Power consumption – Air compressor draws 20A at 12V so 240W if running continuously – Rated for 15% duty cycle – 36W on average – 14Ah battery – will last at least 0.7 hours (longer than endurance race) • Mounting – Solid mount to secure the cylinder position – Eliminates lateral motion Dartmouth Formula Racing 23 23
    24. 24. Shifter - Methodology, Work Accomplished • Shifter control – Moved from Arduino to Vehicle Control Unit (VCU) – VCU already weatherproofed – Eliminated the problem of wires falling out • Spark cut – Program to cut engine spark for time of cylinder travel – Removes all load on transmission to ensure consistent shifting – VCU triggers a relay to ground the kill input on the ignition control module – Will trigger as soon as a paddle is pressed Dartmouth Formula Racing 24 24
    25. 25. Shifter - Testing • Bench test – Ran through the gears in sets of 20 – Listened for shift and monitored wheel speed • Track day tests – Shifting without spark cut – Shifting with spark cut • Neutral – Found neutral on bench at least 50% of the time Dartmouth Formula Racing 25 25
    26. 26. Shifter - Specifications Specification Quantification Baseline Target Actual Cost Price ($) < $1000 <$500 $350 Weight Pounds 5lbs more than last year No weight increase over last year No increase Reliability Consistency of shifting and finding neutral Shifts 98%, finds neutral 50% Shifts 99%, finds neutral 75% 100% bench, >95% outside Durability Number of broken parts during spring testing No failures during testing No failures during testing No failures Size Volume Same size as last year 10% smaller than last year Same as last year Power Requirement Power draw (W) 36W (last year’s system) No increase in power draw Same as last year Speed Time per shift 0.2 seconds 0.1 seconds 0.1 – 0.4 secs Dartmouth Formula Racing 26 26
    27. 27. Drivetrain - Overview • Last year’s configuration was designed to allow the electric motor to start the internal combustion engine • Incorporated a ―launch clutch‖ to disengage the electric motor and engine from the wheels • Chain between engine and motor and belt from motor to differential • Misaligned and difficult to adjust Dartmouth Formula Racing Clutch Last year’s rear drive configuration 27 27
    28. 28. Drivetrain - Specifications Specification Justification Quantification Baseline Target Cost DFR has a limited budget and numerous systems that must be improved Price ($) <$1000 <$500 Weight A lighter car will perform better, all else equal Pounds No increase in weight 10% decrease over 2011 Reliability Must be able to operate consistently. The system should not lose alignment or constantly require adjustment Service time required between track days (hours) <2 hours <1 hour Durability Must be able to operate through testing and competition without failure Number of broken parts during spring testing No failures during testing No failures during testing Size Must leave room for other components that will be installed on the car Volume No increase in size 10% decrease over 2011 Dartmouth Formula Racing 28 28
    29. 29. Drivetrain - Decision Matrix Drivetrain Specification Weight Current System Switch Belt to Chain Clutch-less System Parallel Chains Cost 0.0% 1 0 0 -1 Weight 8.3% -1 -1 1 0 Reliability 21.4% -1 0 0 0 Durability 13.1% -1 0 0 0 Size 11.7% -1 -1 1 0 -1 -0.35 0.35 0 Dartmouth Formula Racing 29 29
    30. 30. Drivetrain - Alternatives 1. Hybrid Type – Series or Parallel 2. Belt or Chain 3. Drivetrain Component Geometry One Chain Two Parallel Chains Two Chains in Series Engine Engine Engine Transmission Electric Motor Differential / Wheels Transmission Chain Chain Electric Motor Transmission Differential / Wheels Dartmouth Formula Racing Chain Electric Motor Chain Differential / Wheels 30 30
    31. 31. Chain Tensioning Adjustable motor and differential Dartmouth Formula Racing 31 31
    32. 32. Drivetrain - Motor Shaft Alternatives • Shaft with welded sprockets - Simple - Machinable • Splined Shaft - Elegant design - Interchangeable sprockets - Extra expense and machining time Electric Motor Assembly Dartmouth Formula Racing Motor Shaft 32 32
    33. 33. Drivetrain - Chain Guards • 0.125‖ x 2½‖ Stock • Combine to cover both chains entirely • Mount to frame and rear engine mount Dartmouth Formula Racing 33 33
    34. 34. Drivetrain - FEA Analysis Electric Motor Shaft Dartmouth Formula Racing 34 34
    35. 35. Weld Analysis • Analyzed the welds between the motor shaft and the sprockets • Static Analysis – Factor of Safety = 1 • Fatigue Analysis – Welds fail due to large bending stresses created by the maximum tension force of the chain of 7000lbf – Calculations demonstrate that no possible weld size, weld material, or shaft material will fix this problem • Future Plan – Conduct a three-point bending stress test to determine at what bending stress the weld will fail – Investigate the problem further and fabricate two to three motor shafts with welded sprockets as reserves Dartmouth Formula Racing 35 35
    36. 36. Drivetrain - FEA Analysis Bearing Mount Dartmouth Formula Racing 36 36
    37. 37. Drivetrain - FEA Analysis Motor Mount Dartmouth Formula Racing 37 37
    38. 38. Drivetrain - Differential • Taylor Race Engineering - 4:1 Automatic Torque Biasing (ATB) Differential • One wheel can have up to 4X the torque of the other wheel • Output Range of 220 hp • 17 lbs including the differential housing and oil Current Differential Dartmouth Formula Racing 38 38
    39. 39. Drivetrain - Specifications Evaluation Specification Quantification Baseline Target Actual Cost Price ($) <$1000 <$500 $478.32 Weight Pounds No increase in weight 10% decrease over 2011 No increase in weight Reliability Service time required between track days (hours) <2 hours <1 hour <15 min Durability Number of broken parts during spring testing No failures during testing No failures during testing No failures during testing Size Volume No increase in size 10% decrease over 2011 No increase in size Dartmouth Formula Racing 39 39
    40. 40. Drivetrain - Overall Evaluation Did we improve over previous designs? – – – – – Easy, lasting chain tensioning No alignment issues Less space used overall No custom parts February completion Dartmouth Formula Racing 40 40
    41. 41. Economic Analysis – Market Analysis • Target Market : Amateur weekend racecar drivers • SCCA has over 55,000 members that compete in over 2000 events every year • NASA has more than 10,000 members in 15 chapters nationwide • Secondary Market: Hybrid industry, FSAE and Formula Hybrid teams, motorcycle and dirt bike enthusiasts • Followed FSAE rules to price components for 1,000 unit per year production Subassemblies Price Manufactured Price Shift Mechanism $865.50 $479.02 Engine $5,381.15 $2,926.37 Drivetrain $3,427.32 $2,085.32 Total $9,673.97 $5,490.71 Dartmouth Formula Racing 41 41
    42. 42. Future Design Work • Final Drive Ratio – Will choose a final drive ratio after more driving, with a better understanding of traction and engine performance • Pedal Package • Gas Tank – Design will be guided by simplicity, the need to place it above the engine, and need to install in it a level sensor • Steering Wheel • Engine Tuning and Efficiency Testing – Carburetor re-jetting and fuel efficiency testing • Manuals and Competition Presentations Dartmouth Formula Racing 42 42
    43. 43. Deliverables 1. Installed the CRF250X with an electric starter so that our racecar starts every time 2. Improved the pneumatic system so that we can shift consistently 3. Redesigned the drivetrain to eliminate complexity and allow for improved alignment 4. Worked with the Electrical Powerplant and Data Management groups to install and test their systems on the racecar Dartmouth Formula Racing 43 43
    44. 44. Moving Picture
    45. 45. Thank you! Professors Douglas Van Citters and John Collier Douglas Fraser Jason Downs Christian Ortiz Graham Keggi Review Board Members Dartmouth Formula Racing 45 45
    46. 46. Questions? Dartmouth Formula Racing 46 46

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